Cystic fibrosis (CF) is a lethal genetic disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The major cause of death in this disorder is lung pathology, caused by neutrophil-dominant inflammation and other insults. This damage leads to remodeling and fibrosis, causing lung dysfunction. Severity of lung disease varies between CF patients carrying the same mutation in CFTR, but is under strong genetic control as shown by twin and sibling studies. This implicates a role for gene modifiers outside the CFTR locus in regulating lung dysfunction. A genome-wide association study (GWAS) identified single nucleotide polymorphisms (SNPs) on chromosome 11, in the 11p13 region, which associate with lung disease severity in CF patients. These SNPs lie in a non-coding region of the genome, suggesting that they impact cis-acting regulatory elements for nearby genes. The gene encoding ets homologous factor (EHF) maps to the 5' end of this intergenic region. Moreover, a region of open chromatin in 11p13 coincides with an enhancer of the EHF gene promoter. EHF is a transcription factor expressed in many epithelial cell types including those lining the airway within the trachea and bronchi, where its expression is increased by inflammatory mediators. EHF can act as a gene activator or repressor, though its targets in lung epithelial cells are largely unknown. The goal of this proposal is to characterize direct targets of EHF genome-wide, and to determine the role of EHF in regulating cell functions important for lung health and disease. This project will test the hypothesis that EHF controls lung epithelial function by regulating genes involved in inflammation and epithelial barrier maintenance. Using primary airway epithelial cells, experiments in the first aim will characterize direct targets of EHF by identifying binding sites for EHF genome-wide and monitoring differential gene expression following EHF depletion. In depth analysis of these targets will identify biological pathways regulated by EHF. In the second aim, experiments will investigate changes in cell functions relevant to immunity and the epithelial barrier in response to modulation of EHF expression. Immune mediator release and resulting neutrophil recruitment will be studied in this context. The role of EHF in control of transepithelial resistance will alsobe investigated. The outcome of this study will characterize a transcription factor that likely has an important role in regulating genes that coordinate lung function in health and disease states.